In lithographic printing, an inked printing plate contacts and transfers an inked image to a rubber blanket, and then the blanket contacts and transfers the image to the surface being printed. Lithographic plates are produced by treating the image areas of the plate with an oleophilic material and insuring that the non-image areas are hydrophilic. In a typical lithographic printing process, the plate cylinder first comes in contact with dampening rollers that transfer an aqueous fountain solution to the hydrophilic non-image areas of the plate. The dampening plate then contacts an inking roller, accepting the ink only in the oleophilic image areas. The press operator must continually monitor the printing process to insure that the correct balance of the fountain solution and the ink is maintained so that the ink adheres to the printing areas of the plate in order to produce a sharp, well defined print.
The industry has long sought an alternative printing process and associated materials and equipment that does not require a dual fountain solution and transfer system. One known alternative is to create waterless plates by applying to the non-image area a silicone rubber having a very low surface energy, which is not wetted by the ink. However, these silicone modified plates are expensive and require specially cooled press equipment since the fountain solution of the traditional two fluid method also serves as a coolant.
To this end, a single fluid ink-water solution has been disclosed in commonly-assigned U.S. Pat. No. 6,140,392, issued Oct. 31, 2000, which is fully incorporated by reference herein.
Additionally, one of the problems with single fluid lithography systems and methods has been the development of a plate cylinder that is capable of separating the emulsified phase from the ink solution of the single fluid ink so that ink adheres to the printing areas of the plate in order to produce a sharp, well defined print.
Accordingly, the present invention provides a printing method utilizing a single fluid ink solution and a plate cylinder having a hydrophilic polymer in the non-image areas that attracts the emulsified fluid of the single fluid ink.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.